SEX DETERMINATION

SEX DETERMINATION The chromosomes which determine sex in the different organisms are called sex chromosomes. ‘Fhe term –sex– refers to the processes that enable species to exchange materials between homologous chromosomes. Ii causes recombination. Recombination is essential to their mechanism for reproduction. Work on inheritance of sex started after discovery of Menders ork in 1900. The discovery of sex chromosomes ...

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Bentham and Hooker Classification system

1 his system was proposed by George Bentham and Joseph Dalton Hooker. They proposed natural classilication system. .[heir system as published ill Genera Plantarum. They divide the seed plants into 202 orders. .[heir system was chiefly based on De Condone. Advantage of Bentham and Booker Classification system: . It is oased on natural classification system. It changed the artificial classification ...

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Carolus Linnaeus Classification system

The classification system of Linnaeus was based on floral characteristics. He chiefly used characters of stamen’s. Therefore, his system is called sexual system. This system is very convenient for the identification of plants. I le presented his classification system in two books. These books are Species Plantarum and Genera Plantarum. Advantages of Linnaeus system: Linnaeus was first to introduced some ...

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Epidermis

EPIDERMIS Epidermis forms the outermost layer of cells on the primary plant body. It is present over stem. roots, leaves, flowers and fruits. In most plant. epidermis is composed of single layer of cells. But two or several layers are also found in different plants. When it is composed of single layer, it is called hypodermis. When it is composed ...

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Xylem and Phloem

XYLEM Xylems are non-living conducting tissues. They conduct water and dissolved salts from root to different parts of plant. Xylem also forms \S ood in plants. It supports plant body. Xylem tissues are present  only in tracheophytes. Composition of XylemXylem is composed of thllow Mg types of tissues only in tracheophytes. Composition of Xylem Xylem is composed of thllow Mg ...

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Sclerenchyma Tissues

The lignified tisries .vhich lack protoplast at maturity are called sclerenchyma. Hey have thick secondary wall. These are main strengthening tissues of plant. Sclerenehyma cells are found in all parts of plant. They: are present in both ground tissues and vascular tissues. Sclerenchyma has two types: Fibers and sclereids (a) Fibers Very long and narrow sclerenchymatous cells with tapering ends ...

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PARENCHYMA AND COLLENCHYMA TISSUES

The group of cells performing some collective function is called tissue. Tissues organize the body of plant for performing different function. Many types of tissues associate with each other to form tissue system. Vascular system is an example of tissue system. The tissues have following characteristics: Tissues are composed of many cells. These cells may be of one type or ...

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Water Absorption

WATER Absorption: of water*, root hairs: .[he absorption of \safer from the soil takes place tlitimigh the root hairs. Ihe root hairs are in contact with the wateriilms on the soil particles. ‘[here is a thin lining of cytoplasm inside the root hair. This cytoplasm encloses a large vacuole filled with cell sap. The Cytoplasm and cell sap of the ...

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Sex Limited Trait

The traits limited to only one sex due to anatomical differences are called a sex limited treat. Such trait affects a structure or function of the body of males or females only. These traits are controlled by sex-linked or autosomal genes. For example: (i).       Genes for milk production in dairy cattle affect only cows. (ii).      Beard growth in humans is ...

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Sex Determination

XY – MECHANISM This pattern of sex determim tion is round in Drosophila, man and many other organisms. (a) Male: Male is XY. Mite is heterogametic. It produces two types of sex-determining sperms. Half the sperms carry X-chromosome and the other half carry Y — chromosome. Chances for both types of sperms are equal. ) Female: Female is XX. Female ...

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